KDIFF - Trồng hoa

Tác giả: RR

Ngôn ngữ: C++

#include <sstream>
#include <iomanip>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <deque>
#include <complex>

#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
#define FORN(i,a,b) for(int i=(a),_b=(b);i<_b;i++)
#define DOWN(i,a,b) for(int i=a,_b=(b);i>=_b;i--)
#define SET(a,v) memset(a,v,sizeof(a))
#define sqr(x) ((x)*(x))
#define ll long long
#define F first
#define S second
#define PB push_back
#define MP make_pair

#define DEBUG(x) cout << #x << " = "; cout << x << endl;
#define PR(a,n) cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl;
#define PR0(a,n) cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl;
using namespace std;

//Buffer reading
int INP,AM,REACHEOF;
#define BUFSIZE (1<<12)
char BUF[BUFSIZE+1], *inp=BUF;
#define GETCHAR(INP) { \
    if(!*inp) { \
        if (REACHEOF) return 0;\
        memset(BUF,0,sizeof BUF);\
        int inpzzz = fread(BUF,1,BUFSIZE,stdin);\
        if (inpzzz != BUFSIZE) REACHEOF = true;\
        inp=BUF; \
    } \
    INP=*inp++; \
}
#define DIG(a) (((a)>='0')&&((a)<='9'))
#define GN(j) { \
    AM=0;\
    GETCHAR(INP); while(!DIG(INP) && INP!='-') GETCHAR(INP);\
    if (INP=='-') {AM=1;GETCHAR(INP);} \
    j=INP-'0'; GETCHAR(INP); \
    while(DIG(INP)){j=10*j+(INP-'0');GETCHAR(INP);} \
    if (AM) j=-j;\
}
//End of buffer reading

const long double PI = acos((long double) -1.0);

int n, k, a[300111];
int l[300111], r[300111];
int nn[22][300111], ln[22][300111], lg[300111];

#define TWO(x) (1<<(x))

void initRMQ() {
    // Build log
    int p = 1, now = 0;
    while (p <= 300000) {
        lg[p] = now;
        p *= 2; ++now;
    }
    FOR(i,1,300000)
    if (lg[i] == 0) lg[i] = lg[i-1];

    // Build level 0
    FOR(i,1,n) nn[0][i] = ln[0][i] = a[i];

    // Build RMQ
    FOR(t,1,20) {
        FOR(i,1,n-TWO(t)+1) {
            nn[t][i] = min(nn[t-1][i], nn[t-1][i+TWO(t-1)]);
            ln[t][i] = max(ln[t-1][i], ln[t-1][i+TWO(t-1)]);
        }
    }
}

int getMin(int i, int j) {
    int t = lg[j - i + 1];
    return min(nn[t][i], nn[t][j-TWO(t)+1]);
}

int getMax(int i, int j) {
    int t = lg[j - i + 1];
    return max(ln[t][i], ln[t][j-TWO(t)+1]);
}

int main() {
    GN(n); GN(k);
    FOR(i,1,n) GN(a[i]);
    if (n == 1) {
        cout << 1 << endl;
        return 0;
    }

    initRMQ();

    int j = 1, len, res = 0;
    FOR(i,1,n) {
        while (j < n && getMax(i,j+1) - getMin(i,j+1) <= k) ++j;

        len = j - i + 1;
        r[i] = max(r[i], len);
        l[j] = max(l[j], len);
        if (len == n) res = n;
    }

    FOR(i,2,n) l[i] = max(l[i], l[i-1]);
    FORD(i,n-1,1) r[i] = max(r[i], r[i+1]);

    FOR(i,1,n-1) res = max(res, l[i] + r[i+1]);
    cout << res << endl;
    return 0;
}

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